Comparative Study of Lightweight Construction Technologies for Roofing

This report provides a comparative analysis of three lightweight construction technologies used for roofing: wood, metal, and felt. It examines the cost of installation, merits, and demerits of each material, along with their environmental impacts. The report highlights the Australian government's promotion of modern construction techniques and the increasing demand for energy-efficient and low-carbon emission building materials. It discusses the shift towards lightweight materials like timber and steel, addressing concerns about their thermal performance. The report also explores the use of phase change materials for thermal energy storage and the application of each technology, including their advantages and disadvantages. The study concludes by emphasizing the economic viability of passive cooling in lightweight roof buildings and the importance of selecting appropriate materials based on specific project requirements and environmental considerations.

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CONSTRUCTION MANAGEMENT
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Contents
INTRODUCTION...........................................................................................................................................2
First Technology in lightweight construction: Use of wood.....................................................................3
Cost of installation...............................................................................................................................3
Merits..................................................................................................................................................4
Demerits..............................................................................................................................................4
Effects on wood on the environment..................................................................................................4
Second Technology: Use of metals as lightweight roof construction......................................................4
Cost of installation...............................................................................................................................5
Merits..................................................................................................................................................5
Demerits..............................................................................................................................................5
Effects on the environment.................................................................................................................5
Third Technology: Use of Felt as a lightweight material for roofing........................................................6
Cost of installation...............................................................................................................................6
Merits..................................................................................................................................................6
Demerits..............................................................................................................................................6
CONCLUSION...............................................................................................................................................7
REFERENCES................................................................................................................................................9
INTRODUCTION
Australian government has been promoting the use of modern techniques of constructions. Most
of these techniques usually allow for the construction processes to be carried out off the site.

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This is not only done in a standardized manner but also speedily. Any sector of the construction
industry has been demanding for energy. All the construction professionals have been advocating
for the use of building materials with lower carbon emission as well as being efficient in the
conservation of the energy. In order to survive in the environment-sensitive construction sector,
engineers are already considering abandoning the traditional building and construction material
like blocks and bricks which have been used for a long time in the roof construction (Torkaman,
Ashori and Momtazi 2014). A lot of attention is shifting to other materials which are regarded to
be lightweight like timber as well as the steel frame. This move is necessitated by the fact that all
the modern buildings or structures already have their thermal performance requirement limit.
Although engineers have considered using lightweight materials as alternatives to conventional
construction materials, there are concerns about their impacts on the internal conditions of the
buildings. It has been discovered that the majority of the materials which are used in the
lightweight construction cannot store energy in the form of hea t(Khowaiter 2015). It is for this
reason that the temperature range within the room or the building keeps varying with a bigger
margin. Scientists too have predicted the temperatures to increase in the next 30 years due to the
effects of global warming and changes in the climate. Summers are expected to be hotter as well
as drier than it has been in the past. This has further raised more concern on the suitability of
these materials. It is a clear indication that buildings may not benefit much from the initiatives of
reduced heat consumptions incorporated in the air conditioning units (Miqueleiz et al.2013).
Technologists are in dilemma as to which option should be used. The first option is the addition
of more mass so that the thermal property of the roofing materials can be improved. The next
option is to employ engineering techniques which consider environmental conservation
measures. It has been considered to be the basis of using phase change materials which can store

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a large amount of thermal energy for every unit mass. Such properties are missing in the
traditional materials for the construction. The phase change materials efficiently store energy
thermally in the form of heat latent, unlike others which emit sensible heat from their surfaces
due to the radiation effects (Kaczmarczyk, Baryła and Bus 2014).
The roofing process using lightweight has been considered helpful in very many situations. The
replacement of the roofs made from glass so that low pitched roofing can be used is just one of
them. Also, similar replacements can be done by the use of timber in the houses which were
initially under other materials so that lightweight structures can be obtained (Hernández et
al.2014). The latest technology is worth being appreciated since it has managed to effectively
include the traditional materials in the lightweight construction (Laborel et al.2014). These
materials include:
First Technology in lightweight construction: Use of wood
Wood has been used in the building and construction industry for a very long time. It is because
of the admirable properties that make it functionally preferred in various aspects particularly
roofing.
Cost of installation
Australia has plenty of wood that is harvested both from natural and planted vegetation. This is
the reason why the cost of the installation is relatively low when compared to other materials like
steel sheets that have been used in the lightweight construction in the past. It is approximated
that the cost maybe $200 for every 800m2.
Merits
It is regarded as one of the cheapest options available locally
There is no addition of weight to the building since the material is light

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This technology is considered to be environmentally friendly in case the harvesting
processes are carried out responsibly (Naji et al.2014).
Demerits
 This particular material is known to be durable when used as a roofing material except
for the cases of the areas that have a lot of moisture with very low temperatures which
favor rotting.
 It is not the best materials to be used in places that experience long seasons of heavy
rainfall. This implies that regular maintenance through replacement will be required
which is very expensive (Allen and Iano 2013).
Effects on wood on the environment
The waste of wood which is obtained from the demolition process as well as the repair process
can be used in several ways which are friendly to the environment. This is because the materials
are biodegradable.
Second Technology: Use of metals as lightweight roof construction
There are technologies of roofing which involves the use of stone coated roof tiles. Such tiles are
very beneficial considering that they function like metal sheets. In some cases, the processes
have considered the use of base materials made of steel since they are strong. The coating may
sometimes be done using aluminum-zinc alloy. The reinforcement of such systems can be done
using resin materials which are sprayed on the surface of the tiles.
Cost of installation
These are precious metals which usually attract additional costs in their manufacturing. Their
properties to resist corrosion have been improved and therefore they are never cheap. The cost of
installation has been approximated as $350 for every 800m2 in the normal Australian markets.

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Merits
 These tiles are very strong and durable
 They are light in weight thus no additional weight is added to the building
 They have improved thermal properties due to the additional material for coating. This is
also important in lowering the noise level in the houses during the moments of rains.
 The materials are corrosion resistant hence last longer with its aesthetic colors
 The process of installation tends to be easier considering that no additional training is
required for the roofer (He et al.2016)
 Its low weight reduces the stresses of using lifting tools during the construction process.
Demerits
 Use of zinc alloy to make the products corrosion-resistant affects the original attractive
color. This is the main reason why most people do not prefer these particular materials
for the roofing process (Khatib 2016).
 The cost of construction using alloyed components is usually high and very few people
can afford it. This implies that its use is meant for a particular class of individuals.
Effects on the environment
Alloys of zinc and aluminum are never biodegradable. This implies that they are capable of
polluting the environment when they are not handled properly. This impact can only be regulated
when the proper collection is done on the suspected destructive wastes.
Third Technology: Use of Felt as a lightweight material for roofing
Felt is considered to be one of the latest technologies which are used in the roofing to achieve
lightweight structures. It is popularity has grown specifically to favor the flat roof construction. It
is made in the form of rolled sheets. They will be laid on the top of the roof structures that
already have the underlays (Grant, Ries and Kibert 2014). The sheets are impregnated with the

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bitumen so that it can be durable as well as waterproof. Other than being light, the proper
installation makes it be weatherproofing. Material science engineers have established the Felt
materials have a latent heat capacity of 320kJ/m2. It is the same concept which is applied when
the gypsum, are used in the manufacture of plasterboards. As a result, it has varying heat fusion
and other specific characteristics which are unique (George and Mulder 2014).
Cost of installation
In Australia, this particular material is not common in the market. It is only being used under
strict and special conditions of the construction. Another reason as to why this material is not
used in the construction is that it must be installed by the only trained roofer and this makes the
cost of installation to be higher again and again. It has been estimated that 800m2 will need $
360 for proper installation which is also weatherproof (Pacheco-Torgal, and Labrincha 2013).
Merits
 Felt roofed structures are generally durable as well as being waterproof.
 Other than being light, they tend to be weatherproof when they are properly installed.
Demerits
 Felt roofing materials have their service life limited to 25 years. After this period, the
surface will start tearing off calling for replacement as part of maintenance and this can
be cheap.
 In order to have Felt roofing material for the installation, skilled labor must be sought.
This is because, in case of incorrect installation, the building's integrity on the roofing
component will be compromised easily (Khatib 2016).
 This type of roofing is best suited for only flat-roofed structures which are very few.

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Effects on the environment
Felt is a potential pollutant of the environment when it is poorly handled. This is because it is
associated with dust production/. A lot of water and chemical additives should be used to
suppress these fumes.
CONCLUSION
Engineers have identified the properties of lightweight structures which include having the
ability to cool down the internal temperatures of the structures. The processes of cooling keep
varying from one technology to another depending on the material used. To have a direct heat
exchanger of the indoor air, passive cooling mechanisms are exploited. This implies that PCM
components will be incorporated in the structure including the making of building furniture and
plasterboards (Chou, Chen and Nguyen 2013).
Fans can be used in the lightweight roofing technology to help in the processes of assisted
passive cooling. They function to accelerate the hat exchange by improving the velocity of the
incoming air across the surface of the PCM. In some extreme cases, engineers have resorted to
using electricity or just absorbent coolers to reduce the room temperatures of the lightweight roof
structures. This is an integral part of the changing of phase technology (Chilton 2013).
The study identified some of the weaknesses of this approach including demand for extra energy
to be used in the fan operation as well as the system of the refrigeration. As a result of this extra
energy demand, the study identified passive cooling in the lightweight roof buildings as the
economically viable options. This is because other than being cost-effective, it is also non-
pollutant to the environment (Bouasker et al.2014). It is important to note that the study only
focused on the three technologies of lightweight roof construction although there are other
techniques for achieving the same. This has been considered to be the basis of using phase

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change materials which can store a large amount of thermal energy for every unit mass (Suzanne
2014).
Such properties are missing in the traditional materials for the construction. The discussing has
again focused on the advantages and disadvantages of every technique of the lightweight roof
construction before recommending the best-preferred areas or suitable conditions for their
applications. In general, the use of lightweight technology to address the issue of energy demand
in buildings has also provided relief on the demand of natural materials for the construction.

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